PEG-uricase will be tested further in experimental animals for its effectiveness in lowering plasma urate levels over extended periods of time. A clinician will begin human studies - gout, hyperuricemia - will be started if we can prepare sufficient enzyme with satisfactory properties of nonimmunogenicity, nonpyrogenicity, and activity. PEG-glutaminase-asparaginase (Achromobacter) will be prepared in quantity, tested for nonimmunogenicity and nonpyrogenicity, and provided to a clinical person for testing for antitumor activity in humans. Immunological studies will be continued to further pinpoint the manner by which polyethylene glycol alters the immune response. Additional coupling procedures for attaching PEG to enzymes will be developed.